A conventional example of the so-called Emergency Locking Retractor (ELR), a webbing take-up device with a locking mechanism for locking a webbing when acceleration of a predetermined value or more has been applied to a vehicle during an emergency, or the like is disclosed in Japanese Patent Application Laid-Open No. 7-101310 and is known.
As shown in FIG. 6, in this webbing take-up device, a wheel shaped member 72 is formed by effecting a curving process on a steel plate having a plurality of circular flanges 71 which can be deformed due to winding/tightening load of the webbing 70. This wheel shaped member 72 is fitted onto the outer circumferential portion of a webbing take-up shaft 74, and the webbing 70 is taken up around the outer circumferential portion of the webbing take-up shaft 74. Accordingly, when the webbing take-up shaft 74 is locked and the winding/tightening load of the webbing 70 increases and becomes a predetermined value or more, the circular flanges 71 deform or collapse due to the winding/tightening load of the webbing 70. The diameter of the webbing take-up portion gets smaller and the webbing 70 is fed out. For this reason, it is possible to feed out a predetermined amount of the webbing 70 without increasing the winding/tightening load of the webbing 70, during which an optimal state of the webbing 70 can be maintained.
However, in this webbing take-up device, a feeding amount of the webbing 70 is determined by a variation amount of the diameter of a take-up portion of the webbing 70, i.e., a collapsing amount of each of the circular flanges 71 in a height H direction thereof. For this reason, in order to increase the feeding length of the webbing 70, the height H of the circular flange 71 must be increased. However, because the whole size of the webbing take-up device is restricted, the height H of the circular flange 71 cannot be increased to a large degree. As a result, it is difficult for the webbing take-up device to obtain an optimal webbing pulling out amount.
In the related art, Japanese Patent Application Laid Open (JP-A) No. 3-159842 discloses an example of a webbing take-up device in which, when the value of load which has been applied to the webbing is high, energy is absorbed by moving a mounting bracket for mounting the webbing take-up device to an inner panel of the device, toward the inner panel. Japanese Patent Application Laid Open (JP-A) No. 64-32260 discloses an example of a webbing take-up device in which, when the value of impact force which has been applied to the webbing is large, the webbing is steadily fed by impact damping means.
In view of the aforementioned facts, it is an object of the present invention to provide a webbing take-up device in which the optimal pulling out amount of the webbing can easily be ensured during an emergency of a vehicle.